They produce their pharmacological actions such as analgesia by binding with receptors located on the neuronal cell membranes. There are three major types of opioid receptors, μ receptor or Mu receptors, κ receptor or kappa receptor and δ receptor or delta receptor. The μ receptor (Mu receptor) which contains three other subtypes of receptors, the μ1, μ2 and μ3 receptors. These exist in brainstems and the thalamus. Activation of these receptors cause sedation, pain relieved and euphoria as well as respiratory depression, constipation and physical dependence. The κ receptor or kappa receptor are present in the limbic system, the diencephalon (part of the forebrain), the spinal cord and the brain stem. Activation of these receptors cause sedation, pain relief as well as loss of breath and dependence. The δ receptor or delta receptors are present widely in the brain, digestive tract and spinal cord. Activation of these receptors can result in analgesics, an antidepressant effect as well as respiratory depression. Morphine has a considerably higher affinity for μ (mu) receptors than for the other opioid receptors where as Tramadol has a weak affinity for µ- and δ-opioid receptors and an even weaker affinity for the κ-opioid …show more content…
The main difference lie within the strength of the drugs and side effects. Tramadol is much weaker when compared to morphine that means the larger amount of tramadol must be administered in order to achieve the amount of pain relief by using smaller dose of morphine. Tramadol has less opioid side effects when comared to morphine but respiratory depression can occur when administered over dose of tramadol or in renal impaired patients. However tramadol is synthetic analgesic that is not chemically related to opioid. Tramadol is not an opioid but it binds into the opoid receptor and produces exactly same effect as an opioid if medication is